george v. voinovich bridge project...mass concrete according to 499.03. develop a thermal control...
TRANSCRIPT
George V. Voinovich Bridge Project
• In larger concrete structural elements, the exterior
surfaces exposed to air or water cool faster versus the
interior core of the element’s.
• This differential cooling can result in internal concrete
stresses where the concrete prematurely cracks which
can reduce the overall service life of the structure
element.
CCG2 ‐‐Mass Concrete ‐‐ ODOT Background
• Theoretical computer models have been
developed which use dimensional, material, and
environmental factors to estimate the elements’
concrete temperatures to be experienced during
its concrete placement and cure period.
CCG2 ‐‐Mass Concrete ‐‐ ODOT Background
• ODOT’s 2013 Specification Item 511 includes
requirements to control thermal cracking in larger
structural elements. (i.e.: Mass Concrete)
• These concrete requirements also reference and
utilize the Item 455 QC/QA Concrete Quality
Control plans.
CCG2 ‐‐Mass Concrete ‐‐ ODOT Background
• ODOT ‐ District 12 has implemented Mass Concrete
requirements previously on four separate
Construction Projects:
o Fulton Road Bridge over the Zoo in 2006
o LAK 90 Bridge over the Grand River in 2007
o Innerbelt CCG1 in 2010
o Innerbelt CCG2 in 2013
o Statewide, there is a much broader sample.
District 12 ‐‐ Mass Concrete History
District 12 ‐‐ Mass Concrete History
Fulton Road Bridge Mass Concrete Thrust Block
District 12 ‐‐ Mass Concrete History
CCG1 Mass Concrete Typical Element
District 12 ‐‐ Mass Concrete History
CCG2 Mass Concrete Typical Element
• District 12 has progressively moved from Special
Provisions, initially in 2006, to the current ODOT
Item 511 Specifications in 2013 for mass concrete.
• The District made adjustments to these Provisions
from the earlier Projects to improve the service
life and constructability of the structures.
District 12 ‐‐ Mass Concrete History
• An example of these progressive changes are: In 2006, the
mass concrete dimensional minimum was 6 feet. In 2010, it
was revised to 4 feet and now with the 2013 ODOT
Specifications, it is set at 5 feet minimum.
• Coincidentally, on current Design‐Builds, ODOT strives for a
4’–11” minimum design dimension for structural elements
to minimize the need for mass concrete pours.
District 12 ‐‐ Mass Concrete History
Innerbelt Mass Concrete Comparison
CCG1 – Contractual
• 4’ or greater dimension• 160F Max Concrete Temp.• 35F or less differential Temp.• 28 Days cure • Project Scope Provisions and
Appendix with Supplemental Spec. requirements
• Maturity Curve was not allowed, added by Change Order
CCG2 ‐ Contractual
• 5’ or greater dimension• 160F Max Concrete Temp.• 36F or less differential Temp.• 28 Days cure • ODOT Item 511 and Item
455 Specification • Maturity curve is allowed by
Spec.
Innerbelt Mass Concrete Comparison
CCG1 – Materials
• 500 lbs. cement min.• 50% Max. slag content• 25% Max. Fly ash content• <50% Pozzolan Materials
CCG2 ‐Materials
• 470 lbs. cement min.• 30% Max. slag content• 15% Max. Fly ash content• <40% Pozzolan Materials
*** CCG1 had some material correlation testing issues trying to achieve a consistent air content. The Project made these concrete material mix changes to address these inconsistent testing results. Achieving better quality results on CCG2.
• Per Spec. Item 511.03A. Mass Concrete Requirements: For concrete components with
a minimum dimension of 5‐ft (1.5‐m) or greater, develop a concrete mix design QC‐4 for
mass concrete according to 499.03. Develop a Thermal Control Plan (TCP) to control
placement of the mass concrete so that the highest maximum internal temperature of
the placed concrete is not greater than 160⁰ F (71⁰ C) and the maximum differential
concrete temperature does not exceed 36⁰F (20⁰C) over 28 days……
• ODOT was aware of two consultant firms which specialize in
this TCP work. Each firm has their own proprietary thermal
computer model and assumptions to develop such Plans.
• CCG1 and CCG2, each had different firms develop their TCP’s.
Innerbelt ‐‐ Mass Concrete TCP
CCG2 ‐‐Mass Concrete Overview
• 10 Pier Caps ‐ approx. 600 cy each
CCG2 ‐‐Mass Concrete Overview
• 20 Individual Pier Footers ‐ approx. 250 cy each
• 2 semi‐integral Abutment diaphragms – 100 cy each
*****
• The Drilled Shafts were not required to be Mass
Concrete on CCG2 as their designed dimension was < 7’.
• The Department had specifically excluded Drilled Shafts
for Mass Concrete on CCG1 in the Bid Provisions.
CCG2 ‐‐ Mass Concrete Overview
Thermal Control Plan (TCP) Requirements:
• Mix Design Analysis
• Procedures to Control Temps
• Sensor Monitoring Plan
Mass Concrete – Thermal Control Plan
Mass Concrete – Thermal Control Plan
Mass Concrete – Thermal Control Plan
Mass Concrete – Thermal Control Plan
Mass Concrete – Plan Execution
Mass Concrete – Plan Execution
Mass Concrete – Plan Execution
Mass Concrete – Plan Execution
Mass Concrete – Plan Execution
Mass Concrete – Plan Execution
0
10
20
30
40
50
60
70
80
90
100
110
0 25 50 75 100 125 150
Tempe
rature(⁰F)
Time(hrs)
Mass Concrete Footer Example Temperature v. Time
Core
Bottom
Top
Differential
Allowable
1. Plan Implementation
2. Schedule/Resource Constraints
Mass Concrete – Best Practices
Plan Implementation
• Integrate thermal system
• Sensor installation and access
Mass Concrete – Best Practices
Mass Concrete – Best Practices
Schedule and Resource Constraints
• Cold/Cool weather impacts
• Formwork / Insulation System
Mass Concrete – Best Practices
• Concrete Supplier – Cuyahoga Concrete Co.
• Mass Concrete Consultant – W. S. Langley, Inc.
• Material Testing – Solar Testing Laboratories, Inc.
• Concrete Monitoring Equipment – FLIR Systems, Inc.
Mass Concrete – Acknowledgements